The present invention relates to an improvement of a fuel supply system provided in the middle of a fuel supply pipe, as described in U.S. Pat. No. 6,390,871 and JP 2013-516576 W (PCT/US2011/020454), to supply liquid fuel stored in a fuel tank to an engine.
When supplying the liquid fuel stored in the fuel tank to the engine, it is necessary to continuously supply fuel even if there is a rapid acceleration or a rapid deceleration, and it is also necessary to prevent evaporation of the fuel due to high temperatures generated by operation of the engine.
In order to address this issue, conventionally, U.S. Pat. No. 6,390,871 proposes an engine control module equipped with two pumps in a reserve tank, for example. This engine control module is provided in the reserve tank with a first fuel pump as a draw-up pump for drawing up the fuel from a fuel tank to a reserve tank and a second fuel pump for feeding the fuel drawn-up into the reserve tank into a fuel rail of the engine at a higher pressure; thus, the engine control module has advantages of saving pipes for a fuel pipe, easy manufacturing, and further prevention of fuel leakage. However, this prior art has two fuel pumps disposed in the reserve tank, and thus has issues that assembly and mounting are cumbersome and the production cost is high.
In order to solve these problems, JP 2013-516576 W (PCT/US2011/020454) proposes a vapor separator (fuel pump). As shown in FIG. 7, a vapor separator (see FIG. 6) is proposed in which there is disposed in the reserve tank RT a high-pressure pump P2 for feeding the fuel drawn-up in the reserve tank RT into the fuel rail of an engine at a higher pressure and there is disposed a low-pressure fuel pump P1 which is constituted by a pulse pump for drawing up the fuel from the fuel tank to the reserve tank RT and is integrally formed on the outside of the reserve tank RT, for example; thus, the vapor separator can be assembled more easily and be provided at a lower price.
However, this fuel supply system (vapor separator) is a system, in which the pulse pump as the low-pressure pump P1 is formed on a housing H having the reserve tank RT integrally and indivisibly, and which has to have two pumps; thus, there is a big problem that the fuel supply system cannot be applied to a system which supplies a sufficient amount of fuel to the engine by using, for example, the reserve tank RT and the second high-pressure pump P2 even when the rapid acceleration or the rapid deceleration occurs.